Synchronizer rings usually are made of a flat sheet by a stamping and drawing method.
One problem of these sheet-metal synchronizer rings consists in centering the same relative to the synchronizer hub of the manual transmission. In contrast to conventional synchronizer rings made of sintered metal or forged synchronizer rings made of brass, which generally have a cylindrical outer surface and thereby can easily be centered in the cylindrical inner cavity of the synchronizer hub, sheet-metal synchronizer rings have a cone-shaped outer surface due to their manufacture. As on shifting of the transmission the synchronizer ring is axially shifted by the selector sleeve in direction of the gear wheel, the centering of the sheet-metal synchronizer ring gets lost due to the taper of the sheet-metal cone towards the smaller diameter. This can lead to a functional impairment of the manual transmission and to a higher wear.
To ensure an exact centering relative to the synchronizer hub also in sheet-metal synchronizer rings, DE 10 2011 015 836 A1 discloses a generic synchronizer ring with a ring-shaped sheet-metal cone, which at an axial end is bent radially to the outside and includes circumferential locking teeth, wherein radially between the locking teeth and the cone ring protrusions are provided for radially centering the synchronizer ring relative to the synchronizer hub.
Proceeding from this prior art, the present invention creates a stable synchronizer ring of particularly simple construction for a synchronization unit of a manual transmission, which is formed of a ring-shaped sheet-metal cone, includes alternative means for radially centering the synchronizer ring relative to the synchronizer hub, and can be manufactured with little procedural expenditure.